The present invention relates to a curable silicone release coating composition. More particularly, the present invention relates to a curable silicone release coating composition which upon exposure to ultraviolet radiation cures into a very coatable release film that is strongly adherent to a variety of substrates and whose release resistance values can be adjusted over a broad range.
Silicone release coatings and silicone-organic copolymer release coatings have been used to impart releasability to the surfaces of paper and various types of plastic films and to the back surfaces of pressure-sensitive tapes and sheets. For example, in Japanese Patent Application Laid-Open Nos. 5-171047 (171,047/1993) and 6-16944 (16,944/1994), addition reaction-curing compositions and UV-curing compositions have been proposed as silicone release coatings.
Furthermore, in Japanese Patent Application Laid-Open Nos. 64-29459 (29,459/1989), 2-298511 (298,511/1990), and 4-323284 (323,284/1992), silicone-organic copolymer release coating compositions have been proposed as addition reaction-curing compositions and UV-curing compositions.
These silicone release coatings do form highly releasing cured films that give release resistance values on the level of 10 to 15 g/5 cm. However, the low surface energy of these cured films causes poor coatability or writability with oil-based inks and they have poor adhesiveness on polyester films. In contrast to this, the films afforded by the cure of silicone-organic copolymer release coatings are highly coatable and writable with oil-based inks and adhere well to polyester films. Unfortunately, since they exhibit release resistance values of about 120 to 410 g/2.5 cm, they cannot provide release resistance values as low as those of the cured films from silicone release coatings.